The rise in the average global temperatures over the past few decades has raised concerns that the warming stems in part from anthropogenic emissions of so‐called greenhouse gases, that is, those gases that trap heat near Earth's surface. Dominant among the greenhouse gases caused by human activity is carbon dioxide, even when the gases are compared in terms of their perturbation to the atmosphere, as in figure 1. is a natural component of the atmosphere, but its concentration has increased by one‐third since the start of the industrial era and continues to rise at about 0.4% per year.
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© 2000 American Institute of Physics.
2000
American Institute of Physics